In vehicles and the like, various electronic control devices, so called engine control units (ECUs), which control an engine, electronic apparatuses and the like, are mounted. For example, in an ECU controlling an injector which performs fuel injection to a combustion chamber, a boosting power supply unit, which supplies a boosting power supply to the injector, is mounted. The boosting power supply unit generates a boosting power supply which boosts a power supply voltage supplied from a battery mounted in a vehicle to operate the injector.
In this type of boosting power supply unit, for example, a boosting coil, which boosts, by switching operation of a switching element, a power supply voltage supplied from a battery, is provided. The boosting coil produces a high output voltage by energy accumulated in the boosting coil through the conduction of the switching element.
Moreover, in the boosting power supply unit, for example, a constant current control system or the like controls the output voltage to be generated. This constant current control system performs on and off operation of the switching element so that an average current value of an inductor current flowing in the boosting coil becomes a preset current setting value.
Note that a voltage control technology by this type of boosting power supply unit has been known, in which a current detecting means collectively detects a current flowing in each converter, and a drive cancelling means cancels only driving signals in a longer driving state when a plurality of converters among converters are in a driving state, thereby performing stable overcurrent operations (e.g., refer to PTL 1).